This invention concerns the non-destructive inspection of materials housed in containers, and more specifically the inspection of such materials using X-ray beams.
It is well-known to carry out non-destructive inspections of materials, including materials in containers, with X-ray beams. US Patents disclosing such apparatus and methods include: U.S. Pat. No. 3,958,078 to Fowler et al.; U.S. Pat. No. 4,350,889 to Lisnyansky; U.S. Pat. No. 5,583,904 to Adams; U.S. Pat. No. 5,805,662 to Kurbatov et al.; U.S. Pat. No. 5,970,116 to Dueholm; U.S. Pat. No. 6,005,912 to Ocleppo; U.S. Pat. No. 6,434,217 to Pickelsimer et al.; U.S. Pat. No. 6,449,334 to Mazess et al.; U.S. Pat. No. 6,453,003 to Springer et al.; and U.S. Pat. No. 6,459,761 to Grodzins et al.
A problem encountered when using such apparatus and systems, especially when inspecting food in containers, is that the geometry of the containers often causes undue lines in detector images thereof, which detract from the quality of such images and, therefore, negatively affect interpretations of the images. None of the apparatus and methods described in the above-mentioned patents adequately overcomes this problem.
A number of the systems described in these patents employ two or more X-ray beams at substantial angles to one another for producing two or more images that can be interpreted from the two different perspectives. This increases an amount of information available for interpreting the images. For example, Ocleppo (U.S. Pat. No. 6,005,912) describes a non-destructive X-ray inspection apparatus for the food industry that moves glass vessels to be examined along a conveyor. A single X-ray emitter produces two beams separated from one another by 90°, each being at a 45° angle to the conveyor, with each having a separate, angled, sensor. Thus, there are two sensors. The two angled sensors ensure that no area of food is detected by just one sensor, but rather will be detected by the two sensors at 90° to one another. Although this solution avoids erroneous lines that may appear in only one view, it is rather complicated and expensive, requiring at least two detectors and a relatively-complex interpretation of two images. Further, it is noted that this apparatus is specialized, in that it is for detecting of jars having particular types of concavities, which most food containers do not have.
It is noted that many X-ray apparatus and methods for inspecting food in containers respectively use only one X-ray beam and one detector so as not to unduly complicate structure and image interpretation. Similarly, many such X-ray inspection apparatus and methods that direct beams at conveyed containers, direct the beams perpendicular to conveying paths. Such a beam, perpendicular to the conveying path, provides a perspective that is most intuitive for image interpretation and that avoids passage of the beam through two adjacent types of materials and two adjacent containers. In this regard, bulk containers are often rectangular in shape, therefore having leading and trailing sides that are also perpendicular to the conveying path. When leading and trailing sides of adjacent containers are close together, an angled beam can pass through the two containers. Similarly, types of materials within the containers are aligned with these sides so that angled beams can pass through two adjacent types of materials.
In addition, such bulk containers often house smaller cases that also have sides perpendicular to the conveying path. Again, these perpendicular sides of the bulk containers and cases cause lines in detector images produced by perpendicular beams that detract from analysis of the detector images.
Thus, it is an object of this invention to provide an X-ray inspection apparatus (as well as a method) that produces an intuitive, easy-to-read detector image from a single X-ray beam of material in conveyed containers; but yet that reduces the effects of lines in the image caused by container sides, particularly for food containers.